Question

Twenty millilitres of a gaseous hydrocarbon (A) was exploded with excess of oxygen in eudiometer tube. On cooling, the volume was reduced by 50ml. On further treatement with KOH solution, there was a further contraction of 40 ml.

The molecular formula of the hydrocarbon (A) is:
A. `C_(2)H_(6)`
B. `C_(2)H_(4)`
C. `C_(3)H_(6)`
D. `C_(3)H_(8)`

Answer 1

Correct Answer - A
`{:(C_(x)H_(y)(g),+ (x + (y)/(4)) O_(2) rarr x, CO_(2)(g) + (y)/(2)H_(2)O(I)),(1ml,(x+(y)/(4))ml,xml-),(20ml,20(x+(y)/(4))ml,20x" ml Contraction"(50 ml)):}`
`CO_(2)` is absorbed in KOH.
`:. 20x = 40 implies x = 2`
`20 ml + 20 (2 + (y)/(4)) =40 + 50`
`20 + 40 + (20 y)/(4) = 90`
`5y = 90 - 60 = 30`
`y =6`
Formula of the compound `= C_(2)H_(6)`